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Artikel ; Online: Distributed feedback lasers using surface gratings in Bragg waveguides.

Janjua, Bilal / Iu, Meng Lon / Yan, Zhizhong / Charles, Paul / Chen, Eric / Helmy, Amr S

Optics letters

2021 Band 46, Heft 15, Seite(n) 3689–3692

Abstract: This Letter presents, to the best of our knowledge, the first report of a narrow-linewidth ∼790- ... ...

Abstract	This Letter presents, to the best of our knowledge, the first report of a narrow-linewidth ∼790-800
Sprache	Englisch
Erscheinungsdatum	2021-07-30
Erscheinungsland	United States
Dokumenttyp	Journal Article
ISSN	1539-4794
ISSN (online)	1539-4794
DOI	10.1364/OL.431292
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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Artikel ; Online: Single-mode Bragg ring laser diodes.

Janjua, Bilal / Lon Iu, Meng / Charles, Paul / Chen, Eric / Helmy, Amr S

Optics letters

2020 Band 45, Heft 9, Seite(n) 2490–2493

Abstract: We have designed and fabricated a monolithic semiconductor ring laser based on a Bragg waveguide structure. Through careful control of the waveguiding, we have overcome the inherent "leaky" nature of this waveguide mode and demonstrated a ring laser ... ...

Abstract	We have designed and fabricated a monolithic semiconductor ring laser based on a Bragg waveguide structure. Through careful control of the waveguiding, we have overcome the inherent "leaky" nature of this waveguide mode and demonstrated a ring laser lasing in the Bragg mode. Best behavior was obtained from lasers with a diameter of 400 µm, where they exhibited output power ${ \gt }{1}\;{\rm mW}$>1mW, in continuous wave (CW) operation. A tangent waveguide provided access to the ring cavity using two ports through evanescent coupling. To meet the stringent waveguiding requirements imposed by the Bragg structure, a two-step etching process, consisting of a shallow-etched coupler and a deep-etched bend section of the ring, was developed in order to reduce the bend and scattering losses. The laser showed a threshold current density of ${\sim}{2.2}\;{{\rm kA/cm}^2}$∼2.2kA/cm
Sprache	Englisch
Erscheinungsdatum	2020-04-28
Erscheinungsland	United States
Dokumenttyp	Journal Article
ISSN	1539-4794
ISSN (online)	1539-4794
DOI	10.1364/OL.387448
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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Artikel: Catalyst-Free Vertical ZnO-Nanotube Array Grown on p-GaN for UV-Light-Emitting Devices

Alwadai, Norah / Ajia, Idris A / Flemban, Tahani H / Janjua, Bilal / Lopatin, Sergei / Mitra, Somak / Ooi, Boon S / Roqan, Iman S / Wehbe, Nimer / Wei, Nini

ACS applied materials & interfaces. 2019 July 25, v. 11, no. 31

2019

Abstract: One-dimensional (1D) structures-based UV-light-emitting diode (LED) has immense potential for next-generation applications. However, several issues related to such devices must be resolved first, such as expensive material and growth methods, complicated ...

Abstract	One-dimensional (1D) structures-based UV-light-emitting diode (LED) has immense potential for next-generation applications. However, several issues related to such devices must be resolved first, such as expensive material and growth methods, complicated fabrication process, efficiency droop, and unavoidable metal contamination due to metal catalyst that reduces device efficiency. To overcome these obstacles, we have developed a novel growth method for obtaining a high-quality hexagonal, well-defined, and vertical 1D Gd-doped n-ZnO nanotube (NT) array deposited on p-GaN films and other substrates by pulsed laser deposition. By adopting this approach, the desired high optical and structural quality is achieved without utilizing metal catalyst. Transmission electron microscopy measurements confirm that gadolinium dopants in the target form a transparent in situ interface layer to assist in vertical NT formation. Microphotoluminescence (PL) measurements of the NTs reveal an intense ZnO band edge emission without a defect band, indicating high quality. Carrier dynamic analysis via time-resolved PL confirms that the emission of n-ZnO NTs/p-GaN LED structure is dominated significantly by the radiative recombination process without efficiency droop when high carrier density is injected optically. We developed an electrically pumped UV Gd-doped ZnO NTs/GaN LED as a proof of concept, demonstrating its high internal quantum efficiency (>65%). The demonstrated performance of this cost-effective UV LED suggests its potential application in large-scale device production.
Schlagwörter	catalysts ; cost effectiveness ; diodes ; gadolinium ; nanotubes ; transmission electron microscopy ; zinc oxide
Sprache	Englisch
Erscheinungsverlauf	2019-0725
Umfang	p. 27989-27996.
Erscheinungsort	American Chemical Society
Dokumenttyp	Artikel
ISSN	1944-8252
DOI	10.1021/acsami.9b06195
Datenquelle	NAL Katalog (AGRICOLA)

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Artikel ; Online: Catalyst-Free Vertical ZnO-Nanotube Array Grown on p-GaN for UV-Light-Emitting Devices.

Alwadai, Norah / Ajia, Idris A / Janjua, Bilal / Flemban, Tahani H / Mitra, Somak / Wehbe, Nimer / Wei, Nini / Lopatin, Sergei / Ooi, Boon S / Roqan, Iman S

ACS applied materials & interfaces

2019 Band 11, Heft 31, Seite(n) 27989–27996

Abstract	One-dimensional (1D) structures-based UV-light-emitting diode (LED) has immense potential for next-generation applications. However, several issues related to such devices must be resolved first, such as expensive material and growth methods, complicated fabrication process, efficiency droop, and unavoidable metal contamination due to metal catalyst that reduces device efficiency. To overcome these obstacles, we have developed a novel growth method for obtaining a high-quality hexagonal, well-defined, and vertical 1D Gd-doped n-ZnO nanotube (NT) array deposited on p-GaN films and other substrates by pulsed laser deposition. By adopting this approach, the desired high optical and structural quality is achieved without utilizing metal catalyst. Transmission electron microscopy measurements confirm that gadolinium dopants in the target form a transparent in situ interface layer to assist in vertical NT formation. Microphotoluminescence (PL) measurements of the NTs reveal an intense ZnO band edge emission without a defect band, indicating high quality. Carrier dynamic analysis via time-resolved PL confirms that the emission of n-ZnO NTs/p-GaN LED structure is dominated significantly by the radiative recombination process without efficiency droop when high carrier density is injected optically. We developed an electrically pumped UV Gd-doped ZnO NTs/GaN LED as a proof of concept, demonstrating its high internal quantum efficiency (>65%). The demonstrated performance of this cost-effective UV LED suggests its potential application in large-scale device production.
Sprache	Englisch
Erscheinungsdatum	2019-07-25
Erscheinungsland	United States
Dokumenttyp	Journal Article
ISSN	1944-8252
ISSN (online)	1944-8252
DOI	10.1021/acsami.9b06195
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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Artikel ; Online: Facile Formation of High-Quality InGaN/GaN Quantum-Disks-in-Nanowires on Bulk-Metal Substrates for High-Power Light-Emitters.

Zhao, Chao / Ng, Tien Khee / Wei, Nini / Prabaswara, Aditya / Alias, Mohd S / Janjua, Bilal / Shen, Chao / Ooi, Boon S

Nano letters

2016 Band 16, Heft 2, Seite(n) 1056–1063

Abstract: High-quality nitride materials grown on scalable and low-cost metallic substrates are considerably attractive for high-power light-emitters. We demonstrate here, for the first time, the high-power red (705 nm) InGaN/GaN quantum-disks (Qdisks)-in-nanowire ...

Abstract	High-quality nitride materials grown on scalable and low-cost metallic substrates are considerably attractive for high-power light-emitters. We demonstrate here, for the first time, the high-power red (705 nm) InGaN/GaN quantum-disks (Qdisks)-in-nanowire light-emitting diodes (LEDs) self-assembled directly on metal-substrates. The LEDs exhibited a low turn-on voltage of ∼2 V without efficiency droop up to injection current of 500 mA (1.6 kA/cm(2)) at ∼5 V. This is achieved through the direct growth and optimization of high-quality nanowires on titanium (Ti) coated bulk polycrystalline-molybdenum (Mo) substrates. We performed extensive studies on the growth mechanisms, obtained high-crystal-quality nanowires, and confirmed the epitaxial relationship between the cubic titanium nitride (TiN) transition layer and the hexagonal nanowires. The growth of nanowires on all-metal stack of TiN/Ti/Mo enables simultaneous implementation of n-metal contact, reflector, and heat sink, which greatly simplifies the fabrication process of high-power light-emitters. Our work ushers in a practical platform for high-power nanowires light-emitters, providing versatile solutions for multiple cross-disciplinary applications that are greatly enhanced by leveraging on the chemical stability of nitride materials, large specific surface of nanowires, chemical lift-off ready layer structures, and reusable Mo substrates.
Sprache	Englisch
Erscheinungsdatum	2016-01-14
Erscheinungsland	United States
Dokumenttyp	Journal Article ; Research Support, Non-U.S. Gov't
ISSN	1530-6992
ISSN (online)	1530-6992
DOI	10.1021/acs.nanolett.5b04190
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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Artikel: Direct Growth of III-Nitride Nanowire-Based Yellow Light-Emitting Diode on Amorphous Quartz Using Thin Ti Interlayer.

Prabaswara, Aditya / Min, Jung-Wook / Zhao, Chao / Janjua, Bilal / Zhang, Daliang / Albadri, Abdulrahman M / Alyamani, Ahmed Y / Ng, Tien Khee / Ooi, Boon S

Nanoscale research letters

2018 Band 13, Heft 1, Seite(n) 41

Abstract: Consumer electronics have increasingly relied on ultra-thin glass screen due to its transparency, scalability, and cost. In particular, display technology relies on integrating light-emitting diodes with display panel as a source for backlighting. In ... ...

Abstract	Consumer electronics have increasingly relied on ultra-thin glass screen due to its transparency, scalability, and cost. In particular, display technology relies on integrating light-emitting diodes with display panel as a source for backlighting. In this study, we undertook the challenge of integrating light emitters onto amorphous quartz by demonstrating the direct growth and fabrication of a III-nitride nanowire-based light-emitting diode. The proof-of-concept device exhibits a low turn-on voltage of 2.6 V, on an amorphous quartz substrate. We achieved ~ 40% transparency across the visible wavelength while maintaining electrical conductivity by employing a TiN/Ti interlayer on quartz as a translucent conducting layer. The nanowire-on-quartz LED emits a broad linewidth spectrum of light centered at true yellow color (~ 590 nm), an important wavelength bridging the green-gap in solid-state lighting technology, with significantly less strain and dislocations compared to conventional planar quantum well nitride structures. Our endeavor highlighted the feasibility of fabricating III-nitride optoelectronic device on a scalable amorphous substrate through facile growth and fabrication steps. For practical demonstration, we demonstrated tunable correlated color temperature white light, leveraging on the broadly tunable nanowire spectral characteristics across red-amber-yellow color regime.
Sprache	Englisch
Erscheinungsdatum	2018-02-06
Erscheinungsland	United States
Dokumenttyp	Journal Article
ZDB-ID	2253244-4
ISSN	1556-276X ; 1931-7573
ISSN (online)	1556-276X
ISSN	1931-7573
DOI	10.1186/s11671-018-2453-1
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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Artikel ; Online: Quantified hole concentration in AlGaN nanowires for high-performance ultraviolet emitters.

Zhao, Chao / Ebaid, Mohamed / Zhang, Huafan / Priante, Davide / Janjua, Bilal / Zhang, Daliang / Wei, Nini / Alhamoud, Abdullah A / Shakfa, Mohammad Khaled / Ng, Tien Khee / Ooi, Boon S

Nanoscale

2018 Band 10, Heft 34, Seite(n) 15980–15988

Abstract: p-Type doping in wide bandgap and new classes of ultra-wide bandgap materials has long been a scientific and engineering problem. The challenges arise from the large activation energy of dopants and high densities of dislocations in materials. We report ... ...

Abstract	p-Type doping in wide bandgap and new classes of ultra-wide bandgap materials has long been a scientific and engineering problem. The challenges arise from the large activation energy of dopants and high densities of dislocations in materials. We report here, a significantly enhanced p-type conduction using high-quality AlGaN nanowires. For the first time, the hole concentration in Mg-doped AlGaN nanowires is quantified. The incorporation of Mg into AlGaN was verified by correlation with photoluminescence and Raman measurements. The open-circuit potential measurements further confirmed the p-type conductivity, while Mott-Schottky experiments measured a hole concentration of 1.3 × 1019 cm-3. These results from photoelectrochemical measurements allow us to design prototype ultraviolet (UV) light-emitting diodes (LEDs) incorporating the AlGaN quantum-disks-in-nanowire and an optimized p-type AlGaN contact layer for UV-transparency. The ∼335 nm LEDs exhibited a low turn-on voltage of 5 V with a series resistance of 32 Ω, due to the efficient p-type doping of the AlGaN nanowires. The bias-dependent Raman measurements further revealed the negligible self-heating of devices. This study provides an attractive solution to evaluate the electrical properties of AlGaN, which is applicable to other wide bandgap nanostructures. Our results are expected to open doors to new applications for wide and ultra-wide bandgap materials.
Sprache	Englisch
Erscheinungsdatum	2018-06-28
Erscheinungsland	England
Dokumenttyp	Journal Article
ZDB-ID	2515664-0
ISSN	2040-3372 ; 2040-3364
ISSN (online)	2040-3372
ISSN	2040-3364
DOI	10.1039/c8nr02615g
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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Artikel ; Online: Droop-free AlxGa1-xN/AlyGa1-yN quantum-disks-in-nanowires ultraviolet LED emitting at 337 nm on metal/silicon substrates.

Janjua, Bilal / Sun, Haiding / Zhao, Chao / Anjum, Dalaver H / Priante, Davide / Alhamoud, Abdullah A / Wu, Feng / Li, Xiaohang / Albadri, Abdulrahman M / Alyamani, Ahmed Y / El-Desouki, Munir M / Ng, Tien Khee / Ooi, Boon S

Optics express

2017 Band 25, Heft 2, Seite(n) 1381–1390

Abstract: Currently the AlGaN-based ultraviolet (UV) solid-state lighting research suffers from numerous challenges. In particular, low internal quantum efficiency, low extraction efficiency, inefficient doping, large polarization fields, and high dislocation ... ...

Abstract	Currently the AlGaN-based ultraviolet (UV) solid-state lighting research suffers from numerous challenges. In particular, low internal quantum efficiency, low extraction efficiency, inefficient doping, large polarization fields, and high dislocation density epitaxy constitute bottlenecks in realizing high power devices. Despite the clear advantage of quantum-confinement nanostructure, it has not been widely utilized in AlGaN-based nanowires. Here we utilize the self-assembled nanowires (NWs) with embedding quantum-disks (Qdisks) to mitigate these issues, and achieve UV emission of 337 nm at 32 A/cm<sup>2</sup> (80 mA in 0.5 × 0.5 mm<sup>2</sup> device), a turn-on voltage of ~5.5 V and droop-free behavior up to 120 A/cm<sup>2</sup> of injection current. The device was grown on a titanium-coated n-type silicon substrate, to improve current injection and heat dissipation. A narrow linewidth of 11.7 nm in the electroluminescence spectrum and a strong wavefunctions overlap factor of 42% confirm strong quantum confinement within uniformly formed AlGaN/AlGaN Qdisks, verified using transmission electron microscopy (TEM). The nitride-based UV nanowires light-emitting diodes (NWs-LEDs) grown on low cost and scalable metal/silicon template substrate, offers a scalable, environment friendly and low cost solution for numerous applications, such as solid-state lighting, spectroscopy, medical science and security.
Sprache	Englisch
Erscheinungsdatum	2017-01-23
Erscheinungsland	United States
Dokumenttyp	Journal Article
ZDB-ID	1491859-6
ISSN	1094-4087 ; 1094-4087
ISSN (online)	1094-4087
ISSN	1094-4087
DOI	10.1364/OE.25.001381
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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Artikel ; Online: Nanomembrane-Based, Thermal-Transport Biosensor for Living Cells.

ElAfandy, Rami T / AbuElela, Ayman F / Mishra, Pawan / Janjua, Bilal / Oubei, Hassan M / Büttner, Ulrich / Majid, Mohammed A / Ng, Tien Khee / Merzaban, Jasmeen S / Ooi, Boon S

Small (Weinheim an der Bergstrasse, Germany)

2017 Band 13, Heft 7

Abstract: Knowledge of materials' thermal-transport properties, conductivity and diffusivity, is crucial for several applications within areas of biology, material science and engineering. Specifically, a microsized, flexible, biologically integrated thermal ... ...

Abstract	Knowledge of materials' thermal-transport properties, conductivity and diffusivity, is crucial for several applications within areas of biology, material science and engineering. Specifically, a microsized, flexible, biologically integrated thermal transport sensor is beneficial to a plethora of applications, ranging across plants physiological ecology and thermal imaging and treatment of cancerous cells, to thermal dissipation in flexible semiconductors and thermoelectrics. Living cells pose extra challenges, due to their small volumes and irregular curvilinear shapes. Here a novel approach of simultaneously measuring thermal conductivity and diffusivity of different materials and its applicability to single cells is demonstrated. This technique is based on increasing phonon-boundary-scattering rate in nanomembranes, having extremely low flexural rigidities, to induce a considerable spectral dependence of the bandgap-emission over excitation-laser intensity. It is demonstrated that once in contact with organic or inorganic materials, the nanomembranes' emission spectrally shift based on the material's thermal diffusivity and conductivity. This NM-based technique is further applied to differentiate between different types and subtypes of cancer cells, based on their thermal-transport properties. It is anticipated that this novel technique to enable an efficient single-cell thermal targeting, allow better modeling of cellular thermal distribution and enable novel diagnostic techniques based on variations of single-cell thermal-transport properties.
Mesh-Begriff(e)	Biosensing Techniques/methods ; Cell Line, Tumor ; Cell Survival ; Humans ; Luminescent Measurements ; Membranes, Artificial ; Nanoparticles/chemistry ; Temperature
Chemische Substanzen	Membranes, Artificial
Sprache	Englisch
Erscheinungsdatum	2017
Erscheinungsland	Germany
Dokumenttyp	Journal Article ; Research Support, Non-U.S. Gov't
ISSN	1613-6829
ISSN (online)	1613-6829
DOI	10.1002/smll.201603080
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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Artikel ; Online: Ultrabroad linewidth orange-emitting nanowires LED for high CRI laser-based white lighting and gigahertz communications.

Janjua, Bilal / Ng, Tien Khee / Zhao, Chao / Oubei, Hassan Makine / Shen, Chao / Prabaswara, Aditya / Alias, Mohd Sharizal / Alhamoud, Abdullah Ali / Alatawi, Abdullah Awaad / Albadri, Abdulrahman M / Alyamani, Ahmed Y / El-Desouki, Munir M / Ooi, Boon S

Optics express

2016 Band 24, Heft 17, Seite(n) 19228–19236

Abstract: Group-III-nitride laser diode (LD)-based solid-state lighting device has been demonstrated to be droop-free compared to light-emitting diodes (LEDs), and highly energy-efficient compared to that of the traditional incandescent and fluorescent white light ...

Abstract	Group-III-nitride laser diode (LD)-based solid-state lighting device has been demonstrated to be droop-free compared to light-emitting diodes (LEDs), and highly energy-efficient compared to that of the traditional incandescent and fluorescent white light systems. The YAG:Ce<sup>3+</sup> phosphor used in LD-based solid-state lighting, however, is associated with rapid degradation issue. An alternate phosphor/LD architecture, which is capable of sustaining high temperature, high power density, while still intensity- and bandwidth-tunable for high color-quality remained unexplored. In this paper, we present for the first time, the proof-of-concept of the generation of high-quality white light using an InGaN-based orange nanowires (NWs) LED grown on silicon, in conjunction with a blue LD, and in place of the compound-phosphor. By changing the relative intensities of the ultrabroad linewidth orange and narrow-linewidth blue components, our LED/LD device architecture achieved correlated color temperature (CCT) ranging from 3000 K to above 6000K with color rendering index (CRI) values reaching 83.1, a value unsurpassed by the YAG-phosphor/blue-LD counterpart. The white-light wireless communications was implemented using the blue LD through on-off keying (OOK) modulation to obtain a data rate of 1.06 Gbps. We therefore achieved the best of both worlds when orange-emitting NWs LED are utilized as "active-phosphor", while blue LD is used for both color mixing and optical wireless communications.
Sprache	Englisch
Erscheinungsdatum	2016-08-22
Erscheinungsland	United States
Dokumenttyp	Journal Article
ZDB-ID	1491859-6
ISSN	1094-4087 ; 1094-4087
ISSN (online)	1094-4087
ISSN	1094-4087
DOI	10.1364/OE.24.019228
Datenquelle	MEDical Literature Analysis and Retrieval System OnLINE

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